JP4902672B2 - Method for separating at least one actinide element from a lanthanide element in an aqueous solution by sequestering and membrane filtration - Google Patents

Abstract

The invention relates to a process for separating, in an aqueous medium, at least one actinide element from one or more lanthanide elements by using at least one molecule which sequesters the said actinide element to be separated and membrane filtration, the said process successively comprising: a) a step of bringing at least one molecule which sequesters the said actinide element in contact with the aqueous medium, the said molecule not being retained in the non-complexed state by the said membrane and being capable of forming a complex with the actinide element to be separated, comprising the said element and at least two of the said sequestering molecules, which complex is capable of being retained by the membrane; b) a step of passing the aqueous medium over the membrane in order to form a permeate on one side, comprising an aqueous effluent depleted of the said actinide element, and a retentate comprising the said complex.

Description

The present invention relates to a method for separating at least one actinide element from one or more lanthanide elements contained in an aqueous waste liquid (waste liquid) derived from, for example, reprocessing of spent nuclear fuel elements.

  The present invention relates to the use of porous membrane filtration techniques, particularly in combination with sequestration techniques, for separating one or more actinides from lanthanides or for separating lanthanides from each other.

  Waste liquids derived from the reprocessing of spent nuclear fuel elements usually contain a large amount of actinide elements that are very harmful to the environment and are generated over a long period of time (usually over three centuries). Moreover, these waste liquids contain a lanthanide element in an oxidized state (III). It is therefore important to carry out the separation of the actinide and lanthanide elements in order to be able to separate the aqueous effluent having a much less actinide element and less harmful to the environment. .

  The use of technology to separate actinide and lanthanide elements is therefore essential to the protection of the environment.

  Originally, actinide elements contained in radioactive liquid wastes rich in lanthanoid elements have been separated by precipitation or liquid-liquid extraction techniques. However, these methods have the serious disadvantage of generating waste that must be processed afterwards. This greatly complicates these methods and makes them very disadvantageous economically.

  To overcome the above drawbacks, consider using a membrane to separate the actinide element in the retentate and the lanthanide element in the permeate by first combining the actinide with the sequestering molecule. Some researchers do.

For example, International Publication No. 00/73521 describes a method for separating an actinide element from a lanthanide element in an aqueous waste liquid by combining sequestration and membrane filtration, and the following is used.
Treating an aqueous effluent comprising actinide and lanthanide with a sequestering molecule that forms, for example, actinide and / or a complex of 1/1 with lanthanide, of the formula:

-On the one hand, membrane filtration of the aqueous waste liquor treated with sequestering molecules in order to obtain a retentate rich in americium and a permeate substantially free of americium.

  When the molecular weight of the sequestering molecule exceeds the cut-off threshold of the film, a phenomenon occurs in which the sequestering molecule is deposited on the surface of the film. If the sequestering molecules are deposited in this manner, the membrane may be clogged, and the membrane permeability may be irreversibly impaired. This concentration phenomenon also affects the retention of the membrane.

To solve this clogging problem, which is contributed by free (ie, uncomplexed) sequestering molecules, the following two alternatives are envisaged.
-Countercurrent cleaning of the film for the purpose of removing organic and inorganic substances deposited on the surface of the film;
-Improvement of the tangential flow rate on the membrane surface of the waste liquid to be treated by improving the supply rate, changing the flow shape and vibrating the membrane surface.

  With respect to the first alternative method, it may not be possible to remove a certain percentage of the material deposited on the surface of the membrane and within the pores, limiting the useful life of these membranes.

  With respect to the second alternative method, all assumed procedures involve additional costs that cannot be ignored.

  The present invention thus provides a method for separating at least one actinide element from a lanthanide element and makes it possible to overcome the disadvantages mentioned above, in particular those associated with clogging of the membrane by the sequestering molecules used. .

In order to solve the above-mentioned problem, a method according to an embodiment of the present invention uses at least one molecule that sequesters at least one actinide element to be separated, and filtration of the membrane, thereby A method for separating the actinide element from an lanthanide element in an aqueous solution,
  a) contacting at least one molecule sequestering the actinide element with an aqueous solution;
b) sequentially passing the aqueous solution through the membrane,
The molecule is not held in an uncomplexed state by the membrane and can form a complex with the actinide element to be separated, the complex comprising the actinide element and at least two sequestering molecules, And can be retained by the membrane;
  In the step of passing the aqueous solution through the membrane, a permeate containing the waste liquid from which the actinide element has been removed is formed on one side, and a retentate containing the complex is formed.

  As mentioned above, the sequestering molecules used in the method of the present invention are selected such that they are not retained by the membrane in the uncomplexed state. One of the selection criteria is the molecular weight of the uncomplexed sequestering molecule, which is advantageously less than the cut-off threshold of the membrane used. The sequestering molecule is selected to form a complex with the actinide element that is sequestered, and the complex includes at least two of the element and the sequestering molecule and is held by a membrane. The retention of the complex is explained by the molecular weight (steric exclusion) of the complex formed which is advantageous if it is above the membrane cut-off threshold and / or the charge sign passes through the solution containing the element to be separated. It can be explained by the fact that the charge of the complex formed, which is advantageously the same as the membrane polarized at, is retained on the surface of the membrane by electrostatic interaction (so-called Donnan exclusion).

  Contrary to conventional methods, the sequestering molecules are not retained by the membrane in an uncomplexed state, so that the sequestering molecules are not deposited on the surface of the membrane and do not clog the membrane.

  Therefore, a direct advantage of the present invention is to select sequestering molecules that can pass through the membrane in an uncomplexed state and can form complexes held by the membrane with each other and with the element to be separated. .

A sequestering molecule that can advantageously be used to separate an actinide element such as americium from a lanthanide element is a monocyclic aromatic compound containing at least two sequestering functional groups on the ring, the functional group being − Selected from COOH, —CONHOH, —SO ₃ H, —PO ₃ H ₂ , —P (O) OHQ, where Q represents an alkyl, hydroxyalkyl or oxoalkyl group. Although it is generally considered undesirable for any sequestering reaction that the atoms of these sequestering functional groups in this type of molecule are arranged in a plane, the inventors are surprised. In particular, it has been shown that such sequestering molecules are effective in separating at least one actinide element from a lanthanide element.

  For example, a monocyclic aromatic compound can contain one or more oxygen, sulfur and / or nitrogen atoms, especially one or more nitrogen atoms in the ring.

The monocyclic aromatic compounds that can be used can contain 6-membered rings. Examples of such compounds include those corresponding to the following general formula.

Where
-A, B and D independently represent a carbon atom or a nitrogen atom;
-X _{1, X 2} are _{independently, -COOH, -CONHOH, -SO 3 H} , -PO 3 H 2, represents -P (O) OHQ group, wherein Q is an alkyl, hydroxyalkyl or oxoalkyl group Represents
-Z ₁ , Z ₂ , and Z ₃ are independently -H, -F, -Cl, -Br, -I, -OH, when A, B, and / or D represent a carbon atom. comprising -OR, -SR, -NHR, -CHO, -COOR, -CONR 1 R 2, -NR 1 R 2, -NR 1 -NR 2 R 3, -R'-SO 2 R, from -SO ₃ R Selected from the group, wherein -R, R ₁ , R ₂ , R ₃ independently represent H, an alkyl or hydroxyalkyl group containing 1 to 6 carbon atoms;
-R 'represents an alkene or hydroxyalkene group containing 1 to 6 carbon atoms.

Specific examples that apply to the definition of the above general formula include those corresponding to the following formula.

In the formula, X ₁ , X ₂ , Z ₁ , Z ₂ and Z ₃ are as defined above.

The compound is in particular a compound corresponding to the following formula:

  This compound is particularly effective when separating americium from lanthanide elements such as europium. This compound forms in particular a complex comprising americium and three sequestering molecules.

The monocyclic aromatic compounds that can be used can also include a 5-membered ring such as a compound corresponding to the following formula:

Where
-A represents a sulfur or oxygen atom;
-X ₁ and X ₂ are independently -COOH, -CONHOH, -SO ₃ H, -PO ₃ H ₂ , -P (O) OHQ (where Q represents an alkyl, hydroxyalkyl or oxoalkyl group) ) Selected from the group consisting of
—Z ₁ and Z ₂ are independently —H, —F, —Cl, —Br, —I, —OH, —OR, —SR, —NHR, —CHO, —COOR, —CONR ₁ R _2. , —NR ₁ R ₂ , —NR ₁ —NR ₂ R ₃ , —R′—SO ₂ R, —SO ₃ R, wherein —R, R ₁ , R ₂ , R ₃ are independently selected. H represents an alkyl or hydroxyalkyl group containing 1 to 6 carbon atoms,
-R 'represents an alkene or hydroxyalkene group containing 1 to 6 carbon atoms.

  The sequestering molecules defined above have a particularly good selectivity for americium compared to lanthanide elements such as europium.

  The number of moles of sequestering molecules is greater than or equal to the equivalent of moles of actinides to be separated.

  As mentioned above, the method according to the invention comprises a method for selectively sequestering an actinide element relative to a lanthanide element, a membrane separation method for step b), more particularly ultrafiltration and Based on a combination of nanofiltration.

  However, the method of the present invention is not limited to ultrafiltration and nanofiltration alone; rather, it forms a barrier between two homogeneous media to allow different components of the fluid (suspension, solute, solvent) It includes any other membrane separation technique that uses a semi-permeable membrane that exhibits unequal resistance to passage. The force that allows certain said components to pass through the barrier comes from pressure gradients (microfiltration, ultrafiltration, nanofiltration, reverse osmosis), concentration gradients (dialysis) or potential gradients (electrodialysis).

  Filtration membranes, particularly nanofiltration membranes and ultrafiltration membranes that can be used within the method of the present invention may be organic, inorganic, or organic minerals. These membranes are permeable to the sequestering molecules of the present invention in the free (ie, uncomplexed) state and must retain the sequestering molecule when the sequestering molecule is complexed with the actinide element or the element to be separated. There is.

  According to the invention, and especially for sequestering molecules as defined above, the membrane used has a cut-off threshold in the range of 250 to 10,000 daltons, more particularly 1000 to 5000 daltons. It is advantageous.

  Specifically, the cut-off threshold of the membrane can be defined as the molar mass of a solid (usually polyethylene glycol) with a retention of 90%, and the unit of this cut-off threshold is usually expressed in daltons.

  The membrane comprises an aromatic polyamide, sulfonated polysulfone, polybenzimidazolone, optionally grafted polyvinylidene fluoride, polyamide, cellulose ester, cellulose ether or perfluoroionomer, combinations of these polymers and at least two of these polymers And at least one material selected from the group consisting of copolymers obtained from these monomers.

  From the viewpoint of morphology, the membrane of the present invention is advantageously helical or planar.

As examples of membranes for carrying out the method of the invention, mention may be made in particular of those sold under the name Desal GH by the company Osmonics. This type of membrane has in particular the following properties:
A cutoff threshold of -2500 daltons,
A surface area of -0.25 m ² ,
-3l. h- ¹ . a maximum permeation volume flow rate of m ⁻² , and − good resistance to irradiation of the membrane (accumulated dose of 1 MGy does not cause visible degradation of the polymer constituting the surface of the membrane).

  Tubing or parallel plate modules, such as those conventionally used in this technology, can be used. For the purpose of collecting permeate, a module that is a flat membrane wound spirally around a hollow tube in which the membrane is perforated is also used.

  Processing conditions such as the pH of the aqueous solution to be treated, the pressure difference, the flow rate of the aqueous waste liquid and the temperature used are adjusted to obtain the desired separation factor.

Step a) is advantageously carried out at a predetermined pH, preferably in the range 1 to 6. This pH can be adjusted by adding a base or acid, preferably NaOH or HNO ₃ .

  The filtration step is usually performed by applying a pressure difference between the two sides of the membrane to collect the permeate from which the actinide element to be separated has been substantially removed and the retentate enriched in the actinide element to be separated. Is done. The pressure difference between the two sides of the membrane varies over a wide interval, but good results are obtained by applying a pressure difference in the range of 1 to 10 bar.

According to another aspect of the present invention, the present invention provides a method for separating at least one actinide element such as americium from one or more lanthanide elements such as europium, preferably by membrane filtration. at least it relates to the use of monocyclic aromatic compounds having two sequestering functional group, the functional group is _{-COOH, -CONHOH, -SO 3 H,} -PO 3 H 2, is selected from -P (O) OHQ in, Here, Q represents an alkyl, hydroxyalkyl or oxoalkyl group.

  For example, a monocyclic aromatic compound may contain one or more oxygen, sulfur and / or nitrogen atoms, particularly one or more nitrogen atoms in the ring.

The monocyclic aromatic compounds that can be used may contain 6-membered rings. Examples of such compounds include those corresponding to the following general formula.

Where
-A, B and D independently represent a carbon atom or a nitrogen atom;
-X _{1, X 2} are _{independently, -COOH, -CONHOH, -SO 3 H} , -PO 3 H 2, represents -P (O) OHQ group, wherein Q is an alkyl, hydroxyalkyl or oxoalkyl group Represents
-Z ₁ , Z ₂ , and Z ₃ are independently -H, -F, -Cl, -Br, -I, -OH, when A, B, and / or D represent a carbon atom. comprising -OR, -SR, -NHR, -CHO, -COOR, -CONR 1 R 2, -NR 1 R 2, -NR 1 -NR 2 R 3, -R '-SO 2 R, from -SO ₃ R Selected from the group, wherein -R, R ₁ , R ₂ , R ₃ independently represent H, an alkyl or hydroxyalkyl group containing 1 to 6 carbon atoms;
-R ^' represents an alkene or hydroxyalkene group containing 1 to 6 carbon atoms.

Specific examples applicable to the definition of the general formula include those corresponding to the following formula.

Here, X ₁ , X ₂ , Z ₁ , Z ₂ and Z ₃ are as defined above.

The compound is in particular a compound corresponding to the following formula:

The monocyclic aromatic compounds that can be used may include a 5-membered ring such as a compound corresponding to the following formula:

Where
-A represents a sulfur or oxygen atom;
-X _{1, X 2} are _{independently, -COOH, -CONHOH, -SO 3 H} , -PO 3 H 2, represents -P (O) OHQ, where Q is alkyl, hydroxyalkyl or oxoalkyl group Represent,
—Z ₁ and Z ₂ are independently —H, —F, —Cl, —Br, —I, —OH, —OR, —SR, —NHR, —CHO, —COOR, —CONR ₁ R _2. , —NR ₁ R ₂ , —NR ₁ —NR ₂ R ₃ , —R ^′ —SO ₂ R, —SO ₃ R, wherein —R, R ₁ , R ₂ , R ₃ are independently selected H represents an alkyl or hydroxyalkyl group containing 1 to 6 carbon atoms,
-R ^' represents an alkene or hydroxyalkene group containing 1 to 6 carbon atoms.

  The sequestering molecules defined above have a particularly good selectivity for americium compared to lanthanide elements such as europium.

  The invention will now be described with reference to the following examples. This is done for illustrative purposes and is not meant to be limiting.

The following examples are implemented with the tangential filtration device shown in FIG. The apparatus includes a double wall glass reservoir 1 having a volume of 1 liter and containing waste liquid 3 to be treated, and a pH meter 2 for measuring the pH of the solution. This liquid storage tank is maintained at an appropriate temperature by the cooling circuit 5. The waste liquid to be treated has a flow rate of up to 900 l. via a pipeline 9 with a gear pump 11 which can be changed up to h ^−1, for protection against possible abnormal high pressures and with a differential pressure adjustment device 13 for limiting the operating pressure to a maximum of 4.5 bar, It is carried from the liquid storage tank 1 to the filtration module 7. On the one hand, the retentate R is extracted from the filtration module 7 via the pipeline 15. On the other hand, the permeate P is withdrawn via the pipeline 17. Pipelines 15 and 17 enable R and P to be transferred to the storage tank 1. The pipeline 15 is equipped with a liquid column meter 19 and a needle valve 20, and the pipeline 17 has a flow meter 23 for measuring the flow rate of the permeate and a pH meter 25 (a composite for measuring the pH of the permeate). (Ag / AgClpH electrode).

  The liquid column meter is an all stainless steel liquid column meter having a glycerin tank calibrated from 0 to 10 bar, and is installed upstream of the needle valve to perform pressure measurement.

  The filtration module consists of a stainless steel membrane holder (see model: Vessel PV1812, SEPRA), and a membrane contained in the membrane holder, which can withstand a pressure of 69 bar and a temperature of 50 ° C. This spiral film (Desari GH, manufactured by Osmonics) has a length of 305.0 mm, a diameter of 47.0 mm, and a shim thickness of 0.71 mm.

This film further has the following characteristics.
A cutoff threshold of -2500 daltons,
A surface area of -0.25 m ² ,
-3l. h- ¹ . Maximum permeation volume flow rate of m- ² , and-good resistance to irradiation of the membrane (accumulated dose of 1 MGy does not cause visible degradation of the polymer that makes up the membrane surface).

Example 1
2,6-pyridinedicarboxylic acid (PDCA) accurately weighed in an amount close to 5.54 mol was added to 0.8 liter of 0.1 mol. Dissolve in sodium hydroxide at a concentration of l- ¹ . Concentrated nitric acid ([HNO ₃ )] = 5.0 mol. The pH of the solution is set to 1.5 by adding l- ^l ). A batch composed of a solution containing the lanthanide element in oxidation state (III), europium tracer ¹⁵² Eu (III), americium tracer ²⁴¹ Am (III) is added to the initial solution.

The batch more particularly comprises the composition shown in Table 1.

The pH is readjusted to 1.3 by the addition of concentrated sodium hydroxide ([NaOH] = 5.0 mol·l ⁻¹ ). The solution is finally introduced into the reactor. The speed of the tangential flow is 6.5 l. In sec- ¹ , the transmembrane pressure difference is set to 1.0 bar and the temperature is set to 20 ° C. By gradually adding concentrated sodium hydroxide during 45 minutes (the time it was estimated that the membrane reached equilibrium when all operating parameters are constant), the pH gradually increases. At each pH stage, permeate and retentate sampling and permeate volume flow rate measurements are made.

  Samples are analyzed by ICP-AES (abbreviation for Inductively Coupled Plasma-Atomic Emission Spectroscopy) to determine the concentration of lanthanide (III) metal. The sample is then analyzed by gamma ray spectroscopy to determine the concentration of americium (III) and europium (III) tracers.

  FIG. 2 shows the various lanthanide (III) metals and americium (III) as a function of pH when the ratio [PDCA] / 3 * ([Ln (III)] + [Am (III)]) is equal to 1. Indicates the retention factor.

  At pH = 1.5, the retention coefficient of lanthanide (III) metal is between 3 and 9%, while the retention coefficient of americium (III) reaches 25%. With increasing pH, the retention coefficients of americium (III) and lanthanide (III) metals increase independently until reaching a maximum of 99% at pH 2.0 and reach a separation value of 24%. On the other hand, the maximum difference in retention between americium (III) and lanthanum (III) reaches 74% at pH = 2.3.

  FIG. 3 shows the change in Am (III) / Ln (III) separation factor as a function of pH, where Ln corresponds to the abbreviation for lanthanide.

  For all lanthanide (III) metals, the Am (III) / Ln (III) separation factor reaches a maximum near pH = 3.0. This maximum value is correspondingly higher when the stability constant of the complex is low. For this reason, the maximum selectivity corresponds to the combination of Am (III) / Ln (III), and its separation factor reaches 20.5. This shows that the method of the invention is particularly suitable for americium (III) separation on lanthanum (III). Conversely, Am (III) / Gd (III) separation is more limited with a separation factor of 3.5.

The retention coefficient is a ratio between a predetermined chemical species retained by the membrane and the concentration of this chemical species in the supplied solution, and is defined by the following equation.

Wherein each of C _P and C _R, the concentration of chemical species in the permeate and retentate.

  The transmission coefficient is defined as the complement of the holding coefficient, and T = 100−R.

The separation factor (SF _{A / B} ) of species A relative to species B is defined by the ratio of these two permeation coefficients.

Where [An] _P and [An] _R are the actinide concentrations in the permeate and retentate, respectively, [Ln] _P is the [Ln] _R is the lanthanide concentration in the permeate and retentate, respectively. is there.

  If both retention factors for actinides are very high (eg> 95%) and the retention factor for lanthanides is as low as possible, the separation factor SF An / Ln is high.

(Example 2)
The amount of europium nitrate close to 1.85 moles (III), 9.2.10 ^-6 mole near the amount of europium tracer ¹⁵² Eu (III), and 5.31.10 ^-4 mol close amount of americium ²⁴¹ Am (III) is dissolved in 0.8 liter of distilled water. By addition of concentrated nitric acid ^{_{([HNO 3] = 5.0mol.l -l}} ), it sets the pH of the solution to 2.0. The solution is then introduced into the reactor. The speed of the tangential flow is 6.5 l. In sec- ¹ , the transmembrane pressure difference is set to 1.0 bar and the temperature is set to 20 ° C. The concentration of sequestering ions is gradually increased by adding a high concentration mother liquor of sequestering molecules ([PDCA] = 1.0 mol.l ⁻¹ ) in 45 minutes. At each concentration step, permeate and retentate sampling and permeate volumetric flow rate measurements are made.

  FIG. 4 shows Am (III) / Eu (III) as a function of the ratio [PDCA] / 3 ([Eu (III)] + [Am (III)]) taking values from 0 to 6 at pH 2.0. Represents the change in the separation coefficient (Sf Am / Eu) and the retention coefficient of Americium Am (III) and Europium Eu (III). At this acidity, when the ratio [PDCA] / 3 ([Eu (III)] + [Am (III)]) is 6.0, the separation factor Sf Am (III) / Eu (III) is 8. 7 is reached.

Example 3
The procedure of this experiment is the same as that of Example 2 except that the pH is 3.0.

  FIG. 5 shows traces of americium Am (III) and macro-concentration Europium Eu (III) as a function of the ratio [PDCA] / 3 ([Eu (III)] + [Am (III)]) at pH 3.0. ) Separation coefficient (Sf Am / Eu) and retention coefficients of americium Am (III) and europium Eu (III).

  At pH 3.0, as a function of the number of PDCA equivalents, the retention factors of americium Am (III) and europium (III) increase separately and eventually reach maximum values above 99 and 95%, respectively. The separation factor reaches a maximum value of 10.2 when the ratio [PDCA] / 3 ([Eu (III)] + [Am (III)]) is 2.0.

1 is a schematic view of an apparatus for carrying out the method of the present invention. The figure showing the retention coefficient of americium (III) and a lanthanide (III) element as a function of pH under the experimental conditions of Example 1. The figure showing the separation factor of americium (III) with respect to a lanthanide (III) element on the experimental conditions of Example 1. FIG. Americium (III) and europium (III) retention factors as a function of the ratio [PDCA] / 3 * {[Am (III)] + [Eu (III)]} at pH 2.0 under the experimental conditions of Example 2 , And the figure showing the change of Am (III) / Eu (III) separation factor (Sf Am / Eu). Under the experimental conditions of Example 3, americium Am (III) and europium Eu (III) as a function of the ratio [PDCA] / 3 * {[Am (III)] + [Eu (III)]} at pH 3.0 The figure showing the change of a retention coefficient and Am (III) / Eu (III) separation factor (Sf Am / Eu).

Claims (13)

A method of separating an actinide element in an aqueous solution from one or more lanthanide elements by using at least one molecule that sequesters at least one actinide element to be separated and membrane filtration. ,
a) contacting at least one molecule sequestering the actinide element with an aqueous solution;
b) sequentially passing the aqueous solution through the membrane,
The molecules are not retained in the uncomplexed state by said membrane, and can form the actinides and complex to be separated, said complex including at least two sequestering molecule and the actinides And can be held by the membrane,
The step of passing the aqueous solution through the membrane is a method of separating the actinide element from the lanthanide element that forms a permeate containing the waste liquid from which the actinide element has been removed on one side and forms a retentate containing the complex.   The method according to claim 1, wherein the actinide element to be separated is americium. The sequestering molecule is selected from —COOH, —CONHOH, —SO ₃ H, —PO ₃ H ₂ , —P (O) OHQ (where Q represents an alkyl, hydroxyalkyl or oxoalkyl group). The method according to claim 1 or 2, which is a monocyclic aromatic compound having at least two sequestering functional groups on the ring.   4. The method of claim 3, wherein the monocyclic aromatic compound contains one or more oxygen, sulfur and / or nitrogen atoms in the ring.   The method according to claim 3 or 4, wherein the monocyclic aromatic compound contains one or more nitrogen atoms in the ring.   The method according to claim 5, wherein the monocyclic aromatic compound is a 6-membered ring. The monocyclic aromatic compound is represented by the following formula:
In the formula,
-A, B and D independently represent a carbon atom or a nitrogen atom;
-X ₁ and _{X 2} are independently _{-COOH, -CONHOH, -SO 3 H,} -PO 3 H 2, with -P (O) OHQ group (wherein, Q is an alkyl, hydroxyalkyl or oxoalkyl group Represent)
If A, B, and / or D represents a carbon _atom, -Z _{1, Z 2} and _{Z 3,} -H independently, -F, -Cl, -Br, -I , -OH, -OR, selected -SR, -NHR, -CHO, -COOR, -CONR 1 R 2, -NR 1 R 2, -NR 1 -NR 2 R 3, -R '-SO 2 R, from the group consisting of -SO ₃ R Wherein —R, R ₁ , R ₂ , R ₃ independently represent H, an alkyl or hydroxyalkyl group containing 1 to 6 carbon atoms,
6. The method of claim 5, wherein -R ^' represents an alkene or hydroxyalkene group containing 1 to 6 carbon atoms. The monocyclic aromatic compound is represented by the following formula:
The method of claim 7, wherein X ₁ , X ₂ , Z ₁ , Z ₂ and Z ₃ are as defined in claim 7. The monocyclic aromatic compound is represented by the following formula:
9. The method of claim 8, corresponding to:   The method according to any one of claims 1 to 5, wherein the monocyclic aromatic compound is a 5-membered ring. The monocyclic aromatic compound is
It corresponds to the following formula,
-A represents a sulfur or oxygen atom;
-X ₁ and X ₂ are independently -COOH, -CONHOH, -SO ₃ H, -PO ₃ H ₂ , -P (O) OHQ (where Q represents an alkyl, hydroxyalkyl or oxoalkyl group) )
-Z ₁ and _{Z 2,} -H independently, -F, -Cl, -Br, -I , -OH, -OR, -SR, -NHR, -CHO, -COOR, -CONR 1 R 2, _{-NR 1 R 2, -NR 1 -NR} 2 R 3, -R '-SO 2 R, is selected from the group consisting of -SO ₃ R,
-R, R ₁ , R ₂ , R ₃ independently represent H or an alkyl or hydroxyalkyl group containing 1 to 6 carbon atoms;
11. The method of claim 10, wherein -R ^' represents an alkene or hydroxyalkene group containing 1 to 6 carbon atoms. Step b) is performed by ultrafiltration or nanofiltration process according to any one of the 請 Motomeko 1 11. Wherein step a) of contacting is carried out at a pH of a predetermined method according to any one of 請 Motomeko 1 to 12.